Inorganic–Organic Framework Constructed by the Intercalation of a Double-Decker Porphyrin Metal Complex into Clay Nanosheets and Its Efficient Dye Adsorption Ability

An inorganic–organic framework composed of layered clay nanosheets bridged by pillar-shaped metal complexes was synthesized via the insertion of a heptacationic pillar-shaped double-decker-type gadolinium porphyrin complex with long alkyl side chains into montmorillonite through a cation exchange reaction. The double-decker-type gadolinium porphyrin complex was distributed homogeneously in the montmorillonite, and the interlayer distance of the montmorillonite was significantly expanded after the interaction. The obtained inorganic–organic framework efficiently adsorbed anionic organic dyes in an aqueous solution, whereas pristine montmorillonite hardly adsorbed these dyes. We found that the dye absorption rate of the obtained inorganic–organic framework was much faster than that of montmorillonites modified with long-chain alkylammonium or pyridinium ions. Therefore, this inorganic–organic framework possesses unique internanosheet gaps that can be utilized for molecular recognition.